Field of the Invention
The present invention relates to a technique to generate an image in accordance with the information indicating a viewpoint.
Description of the Related Art
Techniques to generate an image in accordance with the information indicating a viewpoint have been known. For example, there is a free-viewpoint image generation technique in which synthesizing a plurality of images captured from a plurality of directions generates an image captured by a camera virtually located in the space (hereinafter, referred to as a virtual camera). The user can arbitrarily designate the position and orientation of the virtual camera, and the designated position and orientation of the virtual camera are the information indicating the viewpoint of the free-viewpoint image. In other words, the image captured by the virtual camera depicts the view from the arbitrary viewpoint.
As a method for acquiring the information indicating a viewpoint, there is a method for calculating the position and orientation of the apparatus physically operated by the user. The calculated position and orientation of the apparatus can be used as the information indicating the viewpoint, for example, the position and orientation of the virtual camera described above. Japanese Patent Laid-Open No. 2013-61870 discloses a technique in which a mobile terminal operated by the user captures an area including a two-dimensional marker and calculates the relative position and relative orientation of the mobile terminal to the marker based on the captured image.
However, when the image in accordance with the information indicating a viewpoint is output, the visibility of the output image is sometimes decreased. For example, it is assumed that a viewpoint is determined based on the position and orientation of the mobile terminal calculated by the technique described in Japanese Patent Laid-Open No. 2013-61870, and an image depicting the view from the determined viewpoint is generated and output. In this assumption, even when the user intends to control the position and orientation of the mobile terminal to designate a desired viewpoint by physically operating the mobile terminal, it is difficult to accurately operate the mobile terminal as intended, for example, due to a camera shake. This may generate an unintended inclination in the output image.